Ballast system for submarines



May 17, 1966 Filed March 9, 1964 F. E. RIGSBY ETAL BALLAST SYSTEM FOR SUBMARINES 3 Sheets-Sheet 1 INVENTOR. FRANKLIN E. RIGSBY W ODRO RIGSBY ATTORNEYS May 17, 1966 Filed March 9, 1964 F. E. RIGSBY ETAL 3,251,328

BALLAST SYSTEM FOR SUBMARINES 3 Sheets-Sheet 2 INVENTOR. FRANKLIN E. RIGSBY WOODROW RIGSBY BY j m-cQ, 21w

ATTORNEYS y 1966 F. E. RIGSBY ETAL 3,251,328

BALLAST SYSTEM FOR SUBMARINES 3 Sheets-Sheet 3 Filed March 9, 1964 ELE EI INVENTOR. FRANKLIN E. RiGSBY ATTORNEYS United States Patent Office 3,251,328 Patented May 17, 1966 3,251,328 BALLAST SYSTEM FOR SUBMARINES Franklin E. Rigsby and Woodrow Rigsby, both of 9524 Fritz Road, Fort Wayne, Ind. Filed Mar. 9, 1964, Ser. No. 350,456 11 Claims. (Cl. 11416) The present invention relates generally to submarine ballast systems for varying the displacement of a submarine hull, and more specifically to a relatively simple and inexpensive ballast system especially adapted to a relatively small-sized submarine such as that demanded by the aquatic sportsman.

Submarines have been known to the public for years. Almost all submarines have, as an essential component thereof, a ballast system for varying the displacement of the submarine hull in the Water. Variable displacement permits locomotion beneath the water as well as on the surface. Generally the displacement of a submarine is varied by the means of admitting water to a tank or the like attached to the submarine hull thereby adding weight to the hull. Submarine ballast systems therefore generally comprise a ballast tank or ballast compartment for containing the water added to the hull in segregation of the remaining portion of the hull which is maintained dry, a ballast pump for discharging water from the ballast tank, and necessary conduits for admitting water and exhausting water from the ballast tanks and for the bailing of the dry portion of the submarine hull in case of -ballast tank rupture. Whenever the inside hull pressure varies because of water entering or leaving the ballast tanks, the ballast system should provide a means for returning the internal hull pressure to atmospheric conditions.

Submarine ballast tanks must be capable of holding amounts of Water necessary to equalize the weight of the hull with that of the water displaced. Further, means must be provided to prevent movement of water in the ballast tank as shifting water will vary the center of gravity and therefore change the angular position of the submarine in the water. If this shifting of weight takes place rapidly, the submarine may lurch or lunge in such a manner as to prove dangerous to its occupants. For the prevention of ballast water shifting, prior art ballast tanks must always be kept full. On the other hand, the ballast of a submarine must be variable.

Several diiferent ballast tank constructions have been proposed. One of the most common ballast tank constructions, found in both large and small submarines, is the double submarine hull having an inner hull which resists the water pressure and-is watertight in order to maintain the interior of the submarine dry, and an outer hull which defines a ballast tank between the two hulls. Such a ballast tank is designed so that the complete filling of the ballast tank provides an amount of ballast that is equal to or just under that amount required for submerged operation of the submarine. This type of ballast tank must be completely filled as any air pockets which remain therein will vary the working displacement of the submarine as it is subjected to varying depths and pressures.

In every submarine, a further requirement is the need for a trimming device to make fine adjustments in .the total weight of the ballast or in the positioning of the ballast. Relatively large submarines have compartmented relatively small secondary internal ballast tanks in addition to the main ballast tank just described which can be totally filled or totally exhausted-in order to trim the submarine. Ballast must be added in increments of full compartments in order to .prevent the shifting of ballast; and therefore compartmented ballast tanks are limited in use to relatively large submarines for the reason that each filled compartment must be only a small portion of the total'submarine weight and very small watertight compartments are generally exceedingly expensive to manufacture. -The trimming of a relatively small submarine is usually difficult. Proposals have been made for varying the volume of ballast tanks on relatively small submarines by means of a movable wall portion that operates in piston-like fashion and the insertion of an expandable air balloon mounted in the ballast tank which can be inflated to occupy the excess space within the ballast and thereby prevent the ballast from moving. Neither of these proposals have proved to be satisfactory as the movable wall portion has not been made possible without fairly intricate and mechanical linkages and structure, and the latter requires a submarine to carry either a compressor or a supply of compressed gas to inflate the balloon. Both proposals require space and the compressor a may require a power source, both of which are scarce in small submarines. 7

Another essential component of a submarine ballast system is a means for filling and discharging the ballast tanks with water. In all submarines both the intake conduits and the exhaust conduits must be valved so as to control the flow therethrough. This is mandatory in every case as-the adjustment of ballast is critical to the underwater maneuverability and safety of the submarine.

The small submarine for the sportsman poses problems entirely different to that encountered in large size submarines The above-mentioned difficulty encountered in using compartmented ballast tanks for trimming the ballast of relatively small submarines is only a single example. Another difliculty encountered with relatively small submarines is the lack of power generally available. Most smaller submarines have, because of this reason, many hand-operated devices normally run by electricity or more exotic sources such as nuclear power in the larger submarines. However, as most smaller submarines derive their power from conventional storage batteries, the running of high speed compressors, pumps, or electrically operated valves are usually out of the question as most of the power available is needed to drive the propellers. It is therefore necessary for a relatively small submarine to be designed to conserve power wherever possible. Still another difficulty that must be overcome in building a submarine for the sportsman is the elimination of the usual costly manufacturing procedures involved in fabricating watertight compartments that can be filled and discharged with a high degree of safety to the occupant of the submerged submarine. Generally the fabrication of ballast tanks exterior to the main submarine hull are relatively expensive in that they require sheet steel rolling, fabrication and precise welding, or other constructions using materials such as Fiberglas reinforced plastics. Ballast tank compartments having walls that are movable in piston-like fashion are expensive as complicated mechanical linkages are generally required. It is therefore desirable to provide a simple and inexpensive ballast tank construction that is attached to a means for filling and exhausting the ballast system of the ballast tank, that a means is provided whereby'the inside hull pressure can be equalized with the atmospheric pressure during the submarines submergence and again upon surfacing.

Accordingly, an object of the invention is to provide an 6 improved ballast system especially adapted to a relatively small submarine.

Another object of the invention is the provision of an improved design of a ballast tank to be constructed on the interior of a watertight submarine hull.

Another object of this invention is to provide an improved and simple means for controlling the filling and exhausting of a ballast tank in a safe and reliable manner.

It is an object of the invention to provide an improved ballast tank system incorporating an expandable ballast tank mounted on the interior of a watertight submarine hull having a provision for maintaining atmospheric pressure within the submarine hull and for finely adjusting the weight of the ballast.

Still another object of the invention is to provide an improved ballast tank system for a relatively small submarine that has controls at the optimum position which are easily operated.

Still further an object of this invention is to provide a ballast exhaust system that can also be used for bailing the interior of the submarine.

Further objects and advantages of the invention will be described and illustrated in the following description and the accompanying drawings, and the features of novelty which characterize this invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

The invention in its broader aspects provides a ballast tank comprising a sheet, having elastic properties, sealed to the inner surface of a submarine hull at its periphery thereby forming an expandable envelope-type chamber having as its walls the interior surface of a submarine hull and the elastic sheet; a ballast inlet and exhaust mechanism, having capacity to fill and exhaust the ballast tank relatively rapidly, incorporating features to insure maximum safety and atmospheric pressure within the submarine hull.

In the drawings, drawn to scale:

FIG. 1 is a port side cross-sectional view showing the improved ballast system mounted in a relatively small submarine;

FIG. 2 is a starboard side cross-sectional view showing the improved ballast system shown in FIG. 1;

FIG. 3 is a partial sectional view taken generally along the line 33 of FIG. 2; and

FIG. 4 is a cross-sectional view taken substantially along section line 4-4 of FIG. 1.

Referring now to the drawings, an improved ballast system for relatively small submarines in shown comprising a ballast tank 10, a pump 12 operatively connected to the ballast it an exhaust conduit 14, an intake conduit 16, a bilge conduit 18, and a vent pipe 20 all mounted in a relatively small, cylindrically shaped submarine hull 22.

Ballast tank comprises a sheet 24 of a resilient, elastic, and waterproof material, such as rubber, plastic, neoprene, vinyl or other rubber-like material, which when collapsed, lies in intimate contact with inside floor surface 26 of hull 22. Preferably, sheet 24 is rectangular in shape and is positioned on floor 26 such that its center 28 lies in the proximity of axis 30 drawn vertically through the center of gravity of the hull 22 and the longitudinal axis 32 of the latter. Securing the peripheral margins of the sheet 24 to the hull are four elongated metallic strips 34 and 36, the two strips 34 being flat and strips 36 being V-shaped in cross-section. The two strips 34 are curved so as to conform to the cross-sectional curvature of the hull 22 (more specifically the floor 26 portion thereof) and to engage the opposite end edge portions, respectively of the sheet 24. The remaining two strips 36 are straight and engagingly overlie the opposite longitudinal edge portions, respectively of the sheet 24. The entire length of the edge portions of the sheet 24 are thereby sandwiched between the hull floor 26 and the strips 34, 36 to provide a sealed chamber between the floor 26 and the sheet 24. A plurality of bracket-like clamps 38 are welded or otherwise secured to the inner wall of the hull 22 and have flanges 40 which overlie the strips 34 and 36. These clamps 38 are suitably spaced apart as shown in the drawings and are used in sufiicient number to seal effectively the edge portions of sheet 24 to the hull 22 as will become more apparent from the following description (see FIG. 4). Each flange 40 threadedly receives a clamping bolt 44 therethrough which engages the respective strips 34, 36. All of the bolts 44 are ti htened against the strips 34, 36 thereby compressing the edge portions of the sheet 24 into sealing engagement with the hull 22. This provides a watertight seal between the sheet 24 and the hull 22.

A conventional hand pump 12 is mounted on the starboard side of the hull 22 adjacent to the top portion thereof. An exhaust conduit 14 opens through the hull at one end and connects to the outlet side of the pump at the other end. A conventional one-way check valve 48 is connected with the conduit 14 to prevent back flow into the hull 22 if pump 12 should ever fail. Pump 12 is shown to be hand-operated by means of a handle 50; however, the pump may be power-operated without departing from the scope of this invention.

An inlet conduit 16 connects at one end to the inlet side of the pump 12 and at its opposite end to a bilge conduit 18 which extends to the rearmost portion of submarine hull 22, as shown in FIGS. 2 and 3, and terminates immediately adjacent to the floor 26. A handoperated valve 56 is series connected in the conduit or line 18 and is positioned adjacent to the starboard side. Valve 56 is normally closed for preventing pump 12 from sucking air through conduit'lS from the interior of hull 22. An ordinary pipe T 17 provides for the interconnection of the two conduits or pipes 16 and 18 The remaining end of this T 17 is connected to another pipe T 19 (FIGS. 1 and 2). One end of this T 19 is connected to a pipe 58 (FIG. 2) which leads to the ballast tank 10 (to the space between sheet 24 and floor 26). The remaining end of this T 19 is connected to portion 60 of conduit 16 which leads to the hull exterior. In series with the pipe 58 (FIG. 2) and adjacent to the lower end 64 thereof is a flanged pipe coupling 68 which provides a watertight seal between conduit 58 and the sheet 24. The outer end 72 of the pipe 16, 60 opens through the hull 22 at a location which is normally submerged regardless of whether the hull is surfaced or submerged. In series with pipe 16, 60 are two hand ballast valves 74 and 76 of which valve 74 generally remains open. Valve 76 is normally closed and is used to fill controllably ballast tank 10. Valve 74 is used whenever valve 76 becomes inoperative for preventing water from pouring into the ballast tank 10 or from bursting ballast tank 10 resulting in the uncontrollable flooding of the interior of the submarine. The position at which end 72 of conduit 16, 60 communicates with the exterior of hull 22 should be at a distance sufficiently below the water line on the hull when surfaced to provide a water pressure sufficient to fill ballast tank 10 when the submarine is surfaced.

The upright pipe 58 communicates with ballast tank 10 at a position adjacent to the forward end and lowest portion of the hull 22 thereby being positioned at the opposite end of the hull 22 from the bilge conduit 18. This positioning of the ballast conduit 58 and bilge conduit 18 provides a safety feature that is used if ballast tank 10 bursts, in that the ballast water may be exhausted through either one of the conduits 58 or 18. This provides means for exhausting water collected in the hull 22 no matter what angular position the submarine hull 22 takes should the ballast tank burst.

A slide weight 80 is provided for adjusting the longitudinal angular position of hull 22 in the water. This weight 89 is supported by and slidably mounted on an elongated rod 82 which is secured at the opposite ends thereof to the starboard wall of hull 22. Rod 82 extends parallel to axis 32 for about the full length of hull 22, thereby permitting weight 80 to be positioned in the extremes at either end of hull 22 or at any point therebetween.

A vent pipe 20, which extends to a point above the conning tower 89 of the hull 22, leads through the hull 22 as shown in FIG. 1 and connects to a pipe assembly 21 located inside the hull. The end 86 of this pipe assembly 21 opens into the hull interior. A normally closed hand valve 88 is connected in series with this assembly.

In a specific embodiment of this invention, sheet 24 is made of a vinyl sponge material having a density of approximately 21.6 pounds per cubic foot. Sheet 24 is inch thick and measures 3 feet by 2 feet 9 inches. Hull 22 is 2% feet in diameter, 4 feet 8 inches long and is made of inch steel boiler plate; the communication of inlet conduit 16 with the exterior of hull 22 is 6 inches below the water line; the communication of the exhaust conduit 14 with the exterior of hull 22 is 3 inches below the water line. Slide weight 80 is inches long and weights 25 pounds and is movable along rod 82 to a total of 28 inches.

In operation, submergence is begun by opening the main ballast valve 76 and the snorkel valve 88 simultaneously thereby permitting water to flow through pipes 16, 60 and 58 into the ballast tank 10. When the waterline reaches or just covers. the top of the conning tower or hatch 89, the valve 76 is closed. At this point, the proper amount of ballast water has been added to the ballast tank 10 and the pressure Within the submarine is that of the atmosphere, the vent pipe 20 projecting above the water surface and providing communication between the surface air and the interior of-the hull. Valve 88 is now closed. Slide weight 80 is now positioned so as to level the submarine (i.e., finely adjust the angular trim of the submarine) because of the shift of the center of displacement upon filling of tank 10 and boarding by the submarine operator. Generally this adjustment is a fine adjustment as the positioning of the components of the ballast system and other components in the submarine result in a fairly level submarine whether deeply submerged or surfaced. The ballast system is now fully set for underwater operation.

To surface and to achieve full positive buoyancy, the pilot exhausts the ballast tank 10 by means of pump 12 which is operated by back-and-forth movement of pump handle 50. During this operation, Water in the ballast tank 10 is pumped outwardly through pipes 58, 16, 14, valve 48 and port 46. When the submarine reaches the surface, the vent pipe 20 projects above the water, following which the snorkel valve 88 is then opened. This results in equalizing the pressure within the submarine with that of atmosphere. Pumping should then continue until the ballast tank 10 is empty. Thereupon, the pilot can open the hatch and leave the submarine.

The ballast system of this invention possesses various safety and convenience devices. One of the most important of these devices is the means for bailing out the interior of hull 22 should water accumulate therein. Such water accumulation is dangerous and annoying as it may gravitate to the aft end of the submarine and tilt the submarine to such a degree that slide Weight 80 cannot be moved forwardly far enough to counterbalance the weight of water and to place the submarine in a level position. This water can easily be removed by pumping ballast tank 10 dry and then opening valve 56 and operating pump 12 to exhaust the water through conduits 18 and 14 and out of port 46.

If the sheet 24 should rupture, water can be pumped out of the hull via either of the pipes 58 or 18- by proper operation of the valve 56.

However, uncontrollable forward or aft tilting of the submarine, while submerged, is rendered unlikely by the ballast tank 10 construction inasmuch as the water 6 therein is substantially positionally stabilized. By this is meant that the elasticity and resilience characteristics of the sheet or wall 24 are so selected as to resist deformation or stretching thereof under the force of the contained ballast water, when the submarine is longitudinally or laterally tilted. For example, if it is considered that the chamber 10 contains a volume of water which extends to the perimetral edges thereof, this water will tend to gravitate to the lower end of the chamber 10 if the submarine is tilted. However, gravitational movement thereof is in the main prevented inasmuch as the wall resists localized deformation and by reason of its resilient properties tends to maintain the filled shape of the chamber 10. Thus, instead of the water rushing to one end, the water by and large is maintained in a position spread over the lower portion of surface or floor area 26 of the chamber 10 in the same volumetric shape as if the submarine were level.

Thus, changing the elevational attitude in normal steering (by other mechanism not shown) does not create counterbalancing problems due to shifting of the ballast water.

In achieving the positional stability of the ballast water, the thickness, resilience, stretchability and resistance to deformation of the sheet 24 must be properly selected. These properties will depend somewhat upon the size and shape of the hull 22 as well as the size of the tank 10 and the approximate amount of water needed for ballast. When the tank 10 is empty, the sheet 24 should intimately engage the entire floor area of the'tank as is shown in FIG. 4 by the dashed line of line position 24:: of the sheet 24. Thus, total weight as Well as the other properties of the sheet 24 will resist to a certain extent deformation and ingress of water when the valves 74, 76 are opened. The initial quantitles of water will flow to the lowest longitudinal level of the hull 22 and will distribute over the length of ballast tank 10 at this level. (This distribution maintains the balance of the submarine.) The intimate contact of the sheet 24 with the area of the surface 26 not covered with water in addition to the weight of the sheet 24 will tend to keep the water localized in this distribution. As the tank further fills, this same volumetric distribution will continue; the sheet 24 functioning in cooperation with the arcuate shape of the tank 10 to do this. FIG. 4 illustrates a partially filled chamber 10 and the lateral, equalized distribution of th ballast water.

The foregoing described properties of the sheet 24 may hereafter, in the claims, be refered to as shape-retaining properties.

A further safety feature includes the ballast valve 74, which is located in the ballast inlet conduit between valve 76 and the inlet port 72. fails or the packing around valve 76 should leak, secondary valve 74 may be closed, thereupon insuring against any further difficulty. The second safety valve, valve 48, is located in the exhaust conduit 14 between pump 12 and the communication of exhaust conduit 14 with the exterior of hull 22 through port 46. Valve 48 is an emergency check valve in that pump 12 contains like mechanisms which normally prevent water from flowing into conduit 16; check valve 48 is automatically activated only when pump 12 is actuated thereby forcing water outwardly through port 46.

While there has been illustrated and described a specific embodiment of this invention, further modifications and improvements will occur to those skilled in the art, and it is desired therefore in the appended claims to cover all modifications which do not depart from the spirit and scope of this invention.

What is claimed is:

1. For use in a submarine, a ballast tank construction comprising a hull of cylindrical shape having an interior wall provided with a floor surface of part-cylindrical If ever main ballast valve 76' shape in the bottom thereof, a sheet of rubber-like material superposed on said floor surface and conforming to the curvature thereof, said sheet being rectangular in shape and having the longitudinal edges thereof aligned parallel with the axis of said hull, said sheet extending from near one end of said hull to near the opposite end, the geometric center of said sheet being adjacent to a diameter of said hull drawn through the hulls center of gravity, four elongated rigid framing strips superposed onto the marginal edge portions of said sheet for mounting the latter on said floor surface, a plurality of spacedapart clamping members secured to said interior wall adjacent to said framing strips, said clamping members having flanges overlying said framing strips in spaced relation, respectively, each clamping member having one such flange, each flange t-hreadedly receiving a bolt therethrou-gh which clamps the adjacent portion of the respective strip against said sheet thereby forming a watertight seal around the perimeter of said sheet and an expandable compartment between said sheet and said floor surface, the rubberlike material of said sheet having shape-retaining properties whereby movement of water occupying the space between said sheet and said floor surface is resisted upon longitudinal and lateral tilting movement of said hull, a conduit in said hull connected at one end to an intake port which opens through said hull and at the other end to the compartment between said sheet and said floor, a manually operable valve connected in series with said conduit, the connection between said conduit and said compartment being located midship at the forward end of said hull, a manually operable pump mounted inside said hull and having inlet and outlet portions, a first pipe connecting said inlet portion to said conduit at a location between said valve and said other end, a second pipe leading from said outlet portion to an exhaust port which opens through said hull, a one-way check valve in series with said second pipe, whereby opening of said manually operable valve permits water to flow from said inlet port through said conduit and into said compartment and closure of the last-mentioned valve and operation of said pump results in emptying said compartment of said water via said conduit, said first and second pipes and said exhaust port.

2. For use in a submarine, a ballast tank construction comprising a hull of cylindrical shape having an interior wall provided with a floor surface of part-cylindrical shape in the bottom thereof, a sheet of rubber-like material superposed on said floor surface and conforming to the curvature thereof, said sheet being rectangular in shape and having the longitudinal edges thereof aligned parallel with the axis of said hull, said sheet extending from near one end of said hull to near the opposite end, four elon gated rigid framing strips superposed onto the marginal edge portions of said sheet for mounting the latter on said floor surface, a plurality of spaced-apart clamping members secured to said interior wall adjacent to said framing strips, said clamping members having flanges overlying said framing strips in spaced relation, respectively, each clamping member having one such flange, each flange threadedly receiving a bolt therethrough which clamps the adjacent portion of the respective strip against said sheet thereby forming-a watertight seal around the perimeter of said sheet and an expandable compartment between said sheet and said floor surface, the rubber-like material of said sheet having shape-retaining properties whereby movement of water occupying the space between said sheet and said floor surface is resisted upon longitudinal and lateral tilting movement of said hull, a conduit in said hull connected at one end to an intake port which opens through said hull and at the other end to the compartment between said sheet and said floor, a valve connected in series with said conduit, the connection between said conduit and said compartment being located midship at the forward end of said hull, a pump mounted inside said hull and having inlet and outlet portions, a

first pipe connecting said inlet portion to said conduit at a location between said valve and said other end, a second pipe leading from said outlet portion to an exhaust port which opens through said hull, whereby opening of said valve permits water to flow from said inlet port through said conduit and into said compartment and closure of the last-mentioned valve and operation of said pump results in emptying said compartment of said water via said conduit, said first and second lines and said exhaust port.

3. For use in a submarine, a ballast tank construction comprising a hull of cylindrical shape having an interior wall provided with a floor surface of partcylindrical shape in the bottom thereof, a sheet of rubber-like material superposed on said floo-r surface and conforming to the curvature thereof, said sheet being rectangular in shape and having the longitudinal edges thereof aligned parallel with the axis of said hull, said sheet extending from near one end of said hull to near the opposite end, means for sealing the peripheral edge of said sheet to said floor surface thereby providing an expandable compartment between said floor surface and said sheet, said sheet havin-g shape-retaining properties whereby movement of water occupying the space between said sheet and said floor surface is resisted upon longitudinal and lateral tilting movement of said hull, a conduit in said hull connected at one end to an intake port which opens through said hull and at the other end to the compartment between said sheet and said floor, a valve connected in series with said conduit, a pump mounted inside said hull and having inlet and outlet portions, a first pipe connecting said inlet portion to said conduit at a location between said valve and said other end, a second pipe leading from said outlet portion to an exhaust port which opens through said hull, whereby opening of said valve permits water to flow from said inlet port through said conduit and into said compartment and closure of the last-mentioned valve and operation of said pump results in emptying said compartment of said water via said conduit, said first and second pipes and said exhaust port.

4. For use in a submarine, a ballast tank construction comprising a hull of cylindrical shape having an interior wall provided with a floor surface of part-cylindrical shape in the bottom thereof, a flexible sheet of material impervious to water superposed on said floor surface and normally conforming to the curvature thereof, said sheet extending from near one end of said hull to near the opposite end, means for sealing the peripheral edge of said sheet to said floor surface thereby providing an expandable compartment between said sheet and said floor surface, said sheet having shape-retaining properties whereby movement of water occupying the space between said sheet and said floor surface is resisted upon longitudinal and lateral tilting movement of said hull, and means for selectively introducing water into and exhausting water from said compartment.

5. For use in a submarine, a ballast tank construction comprising an elongated hull having an internal bottom surface which is curved in cross-section, a flexible sheet impervious to water superposed on said bottom surface and normally conforming to the curvature thereof, means securing the perimetral edges of said sheet to said bottom surface in watertight relation thereby providing an expandable compartment between said sheet and said floor surface, the material of said sheet having shape-retaining properties whereby movement of water occupying the space between said sheet and said floor surface is resisted upon longitudinal and lateral tilting movement of said hull, and means for selectively introducing water into and exhausting water from said compartment.

6. In a submarine, a ballast-varying system comprising a ballast tank comprising a pressure-withstanding submarine hull having an interior surface, a flexible sheet impervious to water collapsible into intimate, extended area engagement with a portion of the interior surface of said hull, metallic retaining strips overlying said sheet adjacent to the periphery thereof, a plurality of spaced-apart metallic flanges supported in generally parallel relation to said retaining strips, said flanges having threaded apertures therein, a plurality of abutment screws threadedly inserted into said apertures, said screws urging said retaining strips into contact with said sheet thereby providing a watertight seal between said hull and said sheet, a manually operated pump having exhaust and inlet conduits both of which communicate with the exterior of said hull beneath the water line, a bilge conduit having first and second ends and a valve in between, said first end communicating with said inlet conduit of said pump, said second end communieating with the interior of said hull adjacent the lowest portion of said interior surface forming a means for exhausting water which accumulates in said hull, a ballast conduit having first and second ends, said first conduit end being connected to said inlet conduit between said bilge conduit and the connection of said inlet conduit with the exterior of said hull, said second ballast conduit end communicating with said ballast compartment, a pair of valves operatively connected to said inlet conduit of said pump intermediate said ballast conduit and said communication with said exterior surface of said hull.

7. In a submarine, a ballast-varying system comprising a ballast tank comprising a pressure-withstanding, submersible submarine hull having an interior surface, a

flexible sheet impervious to water collapsible normally into intimate engagement with a portion of the interior surface of said hull, means for sealing the perimetral portion of said sheet to said interior surface, thereby providing a watertight ballast compartment between said sheet and said hull, means for pumping water out of said compartment, means for controllably admitting water into said compartment, a vent tube having first and second ends and a valve in between, the first end of said vent tube communicating with the interior of said hull, the second end of said vent tube communicating with the space above said submarine thereby providing a pressureequalizing means for reducing the pressure within said hull after said ballast tank is filled before submergence and for increasing the pressure within said hull after said ballast tank is emptied while surfacing.

8. For use in a submarine, a ballast tank construction comprising a submarine hull having an interior floor surface which is curved, a flexible membrane superposed on said floor surface, said membrane normally engaging and conforming to said floor surface, means sealing the perimetral portion of said membrane to said floor surface for forming a watertight compartment between said membrane and said floor surface, and means for selectively introducing water into and exhausting water from said compartment, said membrane being of a material having shape-retaining properties whereby water in said compartment is substantially maintained in position.

9. For use in a submarine, a ballast tank construction comprising a submarine hull having an interior floor surface, a. flexible membrane superposed on said floor surface, said membrane normally engaging and conforming to said floor surface, means sealing the perimetral portion of said membrane to said floor surface for forming a watertight compartment between said membrane and said floor surface, and means for selectively introducing water into and exhausting water from said compartment, said membrane being of a material having shape-retaining properties whereby Water in said compartment is substantially maintained in position.

10. For use in a submarine, a ballast tank construction comprising a hull of cylindrical shape having an interior wall provided with a floor surface of part-cylindrical shape in the bottom thereof, a sheet of rubber-like material superposed on said floor surface and conforming to the curvature thereof, said sheet extending from near one end of said hull to near the opposite end, the geometric center of said sheet being adjacent to a diameter of said hull drawn through the hulls center of gravity, at least four eldngated rigid framing strips superposed onto the marginal edge portions of said sheet for mounting the latter on said floor surface, a plurality of spacedapart clamping members secured to said interior wall adjacent to said framing strips, said clamping members having flanges overlying said framing strips in spaced relation, respectively, each flange receiving a means for clamping the adjacent portion of the respective strip against said sheet thereby forming a Watertight seal around the perirneter of said sheet and an expandable compartment between said sheet and said floor surface, and second means for selectively introducing water into and exhausting water from said compartment, the rubber-like material of said sheet being resilient, said sheet resisting deformation and stretching under the weight of the water contained in said compartment, said sheet being deformable under the pressure of water entering said compartment, whereby movement of water in said compartment is resisted upon longitudinal and lateral tilting movement of said hull.

11. For use in a submarine, a ballast tank construction comprising a submarine hull having an interior floor surface, a flexible membrane superposed on said floor surface, said membrane normally engaging and conforming to said floor surface, means sealing the perimetral portion of said membrane to said floor surface thereby forming a watertight compartment between said membrane and said floor surface, and second means for selectively introducing water into and exhausting water from said compartment, the material of said membrane being resilient, said membrane resisting deformation and stretching under the weight of water contained in said compartment, said References Cited by the Examiner UNITED STATES PATENTS 273,851 3/1883 Joplin 114-16 399,693 3/1889 Poore et al. 114-16 1,579,109 3/1926 Haseley 114-16 MILTON BUCHLER, Primary Examiner.

FERGUS S. MIDDLETON, Examiner.

T. M. BLIX, Assistant Examiner. 

9. FOR USE IN A SUBMARINE, A BALLAST TANK CONSTRUCTION COMPRISING A SUBMARINE HULL HAVING AN INTERIOR FLOOR SURFACE A FLEXIBLE MEMBRANE SUPERPOSED ON SAID FLOOR SURFACE, SAID MEMBRANE NORMALLY ENGAGING AND CONFORMING TO SAID FLOOR SURFACE, MEANS SEALING THE PERIMETRAL PORTION OF SAID MEMBRANE TO SAID FLOOR SURFACE FOR FORMING A WATERTIGHT COMPARTMENT BETWEEN SAID MEMBRANE AND SAID FLOOR SURFACE, AND MEANS FOR SELECTIVELY INTRODUCING WATER INTO AND EXHAUSTING WATER FROM SAID COMPARTMENT, SAID MEMBRANE BEING OF A MATERIAL HAVING "SHAPE-RETAINING PROPERTIES" WHEREBY WATER IN SAID COMPARTMENT IS SUBSTANTIALLY MAINTAINED IN POSITION. 